River Life: When the river 'boils,' it must be mullet

Thu, Oct 24, 2013 @ 6:49 pm

A couple of weeks ago, I was standing on the new dock we are building at Jacksonville University with one of my colleagues when the water in front of us erupted with activity. The river was “boiling” with fish breaking the surface.

“Mullet run,” we said almost in unison.

Within seconds, we also became aware that bottlenose dolphin and other unseen predators were feeding on the huge school of fish. What a sight! The dolphin and other fish were herding the mullet into a tight school and then passing through the mass of fish getting their fill for dinner. Birds were hovering over the mass of fish feasting on the bits of fish left by the dolphins.

We watched in awe as the swarm of fish moved past us downstream. The mullet were doing their fall migration out of the river and into the ocean.

Mullet are another one of the interesting species of estuarine animals that inhabit the St. Johns River. They are uniquely adapted to live in the constantly changing salinity of the river in Northeast Florida. There are nine different species of mullet, with striped mullet being the most common. But it is also called black mullet, sea mullet, flathead mullet and gray mullet. We also get white or silver mullet and fantailed mullet.

Mullet have a gizzard-like stomach they use to digest the plant material found on the bottom of the river. They are easier to catch using a cast net than with hook and line, but people commonly do both along the banks of the St. Johns.

Striped mullet are the largest of the local species and can reach 18 inches long and weigh 3 pounds. White mullet tend to be smaller and are found in somewhat fresher water. But both species have to leave the estuary in the fall to migrate offshore. There they will spawn, and then the larvae and juveniles will move back into the river in the spring. Shrimp show the same life cycle.

Fish that live in fresh water but migrate to the sea to reproduce are called catadromous. They are opposite of such species as salmon that are anadromous; they live in the sea but migrate to fresh water to reproduce.

One reason we like mullet is that they are good to eat. I love smoked mullet, plain or in a spread, but fried is fine, too.

ASK RIVER LIFE

With all the news about toxic blue-green algae and flesh-eating bacteria, is it safe to eat fish from the St. Johns River?

In general, it is safe to eat fish and shrimp from the St. Johns, but use common sense. The blue-green algae are a fresh water species, while the Vibrio species, often called the flesh-eating bacteria, is more marine. So you are not likely to encounter both species at the same place. If you see visible green algae in the water, avoid contact for you or your pets.

I do not recommend fishing in areas where you can see the algae. But if there are no visible algae, I suggest you wash your catch with fresh, clean water before cleaning it. As for the flesh-eating bacteria, always be careful if you have any cuts or open sores. Wash with plenty of soap and clean water when you get out of the water. If you do get a cut, clean the area thoroughly and rinse with something like hydrogen peroxide and apply a topical antibiotic ointment.

Email A. Quinton White, executive director of Jacksonville University’s Marine Science Research Institute, with questions about our waterways at qwhite@ju.edu. For more on the MSRI, visit ju.edu/msri.